The present invention relates to a structural element for thermal insulation.
The prior art already discloses various embodiments of structural elements for thermal insulation with a separate compressive-force-distributing element which ensures that the compressive force can be transmitted over as large a surface area as possible between load-bearing element and adjoining structural part. Thus, in the early days of such structural elements for thermal insulation, load-bearing elements had a load-bearing bar passing through the insulating body plane and load-bearing plates welded onto the end sides of the load-bearing bar, see for example DE-A-41 03 278.
In the subsequent period, however, designs were also proposed in which the load-bearing webs and the compressive-force-distributing elements were arranged movably with respect to one another, as is described, for example, in DE-A-40 09 987, where the load-bearing web is formed of a metal bar adjoined by sleeve-like compressive-force-distributing elements on the end sides, and the load-bearing web and the two compressive-force-distributing elements are articulatedly connected to one another—at least after a mutual positional securement provided for mounting purposes has been removed. This positional securement comprises end projections of the load-bearing web which extend in corresponding openings in the sleeve-like compressive-force-distributing elements and are fixed there in the form of rivets. This ensures that these three elements, that is to say the load-bearing web and the end compressive-force-distributing elements maintain the position predetermined or intended for them until after the attachment of the adjoining structural parts and until the first actual loading case, which leads to a lateral shearing movement of these rivet-like projections. A disadvantage here, however, is that the shearing can in no case take place flush with the end surface of the load-bearing elements and that also the opening for the position-securing projection is provided exactly in the region where the load-bearing web bears against the compressive-force-distributing element, that is to say an optimum movement and force-introduction surface is likewise not available there. Consequently, in this embodiment known from DE-A-40 09 987, the compressive-force-distributing element can admittedly transmit compressive forces over a large area and introduce them into a load-bearing web which is correspondingly optimized in terms of thermal insulation and has as minimum a cross section as possible, and also compressive-force-distributing elements and load-bearing webs can participate in mutual relative movements in a virtually transverse-force-free manner as a result of the articulated connection without there resulting in an impairment of the function in the compressive-force transmission. However, the compressive-force transmission is in need of improvement as a result of the disturbed or less optimized mutually facing bearing faces.
In the prior art, DE-A-196 27 342 discloses a further embodiment of a load-bearing element with a compressive-force-distributing element in which the compressive-force-distributing element comprises a plate-shaped structural part which is connected by a dovetail-shaped positive connection to the end side of an associated load-bearing web and can thus follow relative movements running in the horizontal direction in a virtually transverse-force-free manner, while at the same time maintaining the compressive-force transmission function. Although the abovementioned dovetail-shaped configuration of the positive connection between compressive-force-distributing element and load-bearing web ensures on the one hand a good positional securement in the installed and transported state, on account of the numerous large-area bearing regions between compressive-force-distributing element and load-bearing web it leads very quickly to constraints, especially if no exact horizontal relative movement between load-bearing element and associated structural part takes place, but a, for example, slight inclination or tilting. The constraints arising here lead to corresponding transverse forces right up to destructions of the load-bearing web or the compressive-force-distributing element in the mutual bearing region.
Furthermore, it should be noted that in the meantime the known solutions with an additional compressive-force-distributing element have succeeded in optimizing the compressive-force transmission by structural elements for thermal insulation of the generic type and nevertheless in not or only barely preventing temperature-induced relative movements between the adjoining structural parts. For all the targeted optimization of the compressive-force transmission and simultaneous maintenance of movability, however, in the past a further optimization with regard to thermal insulation has moved somewhat out of focus, which since the beginning was the main reason for the developments in the field of structural elements for thermal insulation. In this regard, the cross-sectionally reduced load-bearing webs of the prior art were already solidly based on the finding that a better thermal insulation is associated with as small a cross-sectional area as possible in the region of the load-bearing web. In other words, the smaller the cross section in a given load-bearing web material, the smaller also the heat transfer, that is to say the heat transmitted by the load-bearing web.
Nevertheless, however, in order to maintain the compressive-force transmission required, a certain degree of force-introduction surface at the ends is required. For this reason, the prior art discloses load-bearing elements in which the load-bearing webs, with a reduced cross-sectional area in a central region, are again provided at the ends with a larger cross section, see for example EP 1 225 282 A2.
Taking this as the starting point, the present invention is based on the object of making available a structural element of the type mentioned at the outset which is optimized in terms of the compressive-force transmission on the one hand and the thermal insulation on the other hand while maintaining the absorption of relative movements in the region of the load-bearing element.